1. Technical Field
The present invention relates in general to graphics display in data processing systems and in particular to graphics display in multiple graphics modes in a data processing system. Still more particularly, the present invention relates to supporting multiple graphics modes within a data processing system without reinstalling graphics device drivers for each mode or utilizing specialized device drivers supporting multiple modes.
2. Description of the Related Art
Support for standard Video Graphics Array (VGA) modes is provided at the register level in most contemporary graphics adapters for data processing systems. Although the definition of Super VGA (SVGA) modes--defined in terms of resolution, color-depth, and video timings--has been somewhat standardized, there is no standard register-level compatibility for SVGA video modes.
Nearly all currently-available personal computer graphics adapters provide standard VGA graphics modes, in addition to other SVGA graphics modes which are specific to the adapter. A graphics device driver for a specific graphics adapter invariably supports only the device-dependent SVGA modes provided by the adapter. A separate VGA driver needs to be installed to support the standard VGA graphics modes. Thus, while an SVGA graphics device driver usually allows the user to switch between different SVGA modes without installing difference devices drivers, the user cannot select a VGA graphics mode without explicitly installing a different device driver. The most common technique for switching between standard (e.g., VGA) and specialized (e.g., SVGA) graphics modes in a data processing system is to replace (i.e. reinstall) the graphics device driver. Another alternative is to include support for both standard and specialized modes in the same device driver.
As new graphics device standards develop on the personal computer and other workstation platforms, similar situations may be expected to arise. It would be desirable, therefore, to provide support for multiple standard and specialized graphics modes in a data processing system without replacing device drivers or employing specialized device drivers.